American Airlines joins United to extend cancellation of Boeing 737 Max flights after deadly crashes

American Airlines announced Sunday that it will extend its cancellation of flights using the Boeing 737 MAX until Dec. 3.

Until then, the airline said in a press release it is canceling approximately 140 flights per day and rebooking or refunding travelers.

American joins another major U.S. carrier, United Airlines, in pushing back plans to bring the embattled Boeing 737 Max into rotation. United doesn't plan to use the aircraft until Dec. 19.

Southwest Airlines announced it grounded its supply through 2020.

"American Airlines remains confident that impending software updates to the Boeing 737 MAX, along with the new training elements Boeing is developing in coordination with our union partners, will lead to recertification of the aircraft this year," the company said, adding that it is in contact with the Federal Aviation Administration (FAA), Department of Transportation (DOT) and National Transportation Safety Board (NTSB).

The 737 Max was grounded after two deadly crashes. The first crash involved a Lion Air flight from Jakarta, Indonesia, which left 189 people dead in October 2018. Then an Ethiopian Airlines flight crashed and killed all 157 people on board in March.

Boeing has been working on software changes ever since, and the aircraft has been out of commission much longer than anticipated.

American Airlines had a fleet of 24 Boeing 737 Max 8's when the planes were grounded.

The company said it will contact affected customers by email or telephone, and customers who used a travel agent will be contacted by their agency.

Boeing reportedly told suppliers in July that it plans to boost production of its 737 jet model in 2020.